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Bob Harper

Bob Harper

Joined on December 20, 2004

Last Post on August 31, 2014

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putty vs sillycone

@ August 7, 2013 10:07 PM in Plumbers putty or silicone?

Since the strainer is considered replaceable, use putty. It has worked for generations. Sealing the basin to the counter should be silicone unless expressly forbidden by the counter fabricator. Choose the correct silicone, though. Acid cure silicones are suitable for thin joints where it won't corrode the adjoining materials and acts as an adhesive. Thicker joints >1/16" or so should be a neutral cure silicone which is better at gap filling but not very adhesive. When laid in a thick bed, acid cure silicones tend to skin over without curing the inside. Neutral cure will cure throughout quickly. Make sure the caulk is NSF approved. If you really hate silicones like me, you might consider a polyurethane caulk instead.

best practices

@ August 5, 2013 11:54 PM in washing machine drain hose problem

I recommend a single lever control on the hot and cold inlet water to braided stainless steel FloodSafe hoses to Sioux or Oatey water hammer arrestors at the water inlet valve. The washer should sit in a pan that contains a simple battery powered wet alarm wired up somewhere central in the occupied space where it will be heard. The drain should discharge across an air gap into an approved receptacle such as a standpipe with trap and vent or a utility sink. I would install ball valves upstream of the single lever control so its easy to replace the valve body. 


@ July 30, 2013 2:29 PM in Gas Pressures

Since most mfrs. design, construct, test and list their appliances to a certain minimum inlet pressure under full load, I use this against low inlet pressure issues with utilities. I simply take the rating plate data, which clearly states a minimum inlet pressure and show the utility. When they balk, I send them a certified letter return receipt informing them they will be held liable for any operational problems not limited to but including delayed ignition, flame rollout, sooting, carbon monoxide production, premature failure of appliance components such as the heat exchanger,  low heat output, low operating efficiency, adverse emissions, and inability of the appliance to perform as tested and listed. Therefore, the local AHJ or Fire Marshal, who gets a Cc of this letter, is requested to Tag Out/ Lock Out the building as being uninhabitable and immediately hazardous to occupancy and in accordance with the International Fire Code. In the case with rental occupancies, the tenants will then have a clear case against the landlord and utility for marketing an uninhabitable space due to the hazards this condition presents. I further state that now being so informed, should any incidents result in personal injury, death or major property damage, somebody at the utility may face not only civil charges but criminal charges for reckless endangerment, gross negligence, and fraud for not providing adequate fuel while posing as a fuel supplier.

The problem usually gets resolved immediately at no cost to the client.

hate those indoor lakes!

@ July 12, 2013 12:41 PM in Medical Examiner in Utah amazed!

It would seem there could be several mechanisms for CO poisoning what "at the lake". As for CO from an indoor lake, you could reference the Zamboni at an ice rink I guess ;-)


@ June 24, 2013 6:23 PM in 6" Boiler Exhaust w/ 5" chimney liner. how bad is this?

A draft regulator such as a barometric damper is adjusted to maintain a certain measured draft pressure. Changing the size of the baro. does not in and of itself change draft pressure.

Yes, efficiency is affected by airflow through the appliance but we're talking about the liner, which is not always the same thing. As long as you have a consistent draft pressure in the vent and it is not blocked physically or by a high draft induced "curtain effect" such as seen with some draft hoods, a rather consistent amt. of excess air will flow through the burner compartment and thus not change the combustion efficiency. The efficiency of the appliance itself, too remains essentially unchanged as long as their is a steady draft pressure prior to the draft regulator and there is positive flow up the chimney/ vent. Once you have the venting under control, you can look to firing and heat transfer to possibly improve efficiency. Personally, I'd be more concerned about the pump speed/ delta T than the venting and how the burner is set up. An underfired burner will cost you a lot more in oil than any minor change in chimney liner diameter.

I have been advocating combustion analysis here for years. I didn't mention it I guess because I've grown weary of repeating advice that really shouldn't need to be stated over and over. You set up the appliance by full combustion analysis once you have been certified to do it. That includes more than just the O2 reading but yes, you read O2 and don't worry about CO2 as we were all lead to follow for years.

If the liner is slightly oversized but still a thin-walled metallic liner, it should heat up quickly to establish a strong draft pressure. A grossly oversized flue or an high mass masonry flue that has cooled down since the last firing, will rob BTUs as it tries to dry out and warm up as well as trying to push that push-pop slug of cold dense air up out of the flue to establish positive flow. Notice I didn't say "draft" which is a mis-used term.

I find it interesting in the land of regulation that Mass. would allow a bending of the national codes on this. How do they determine the BTU capacity of an oil liner? If by charts, which? If by performance, by which method to what standard? Just curious.


@ June 23, 2013 7:53 PM in 6" Boiler Exhaust w/ 5" chimney liner. how bad is this?

The IRC requires the liner be the same size as the appliance collar or larger. That would start at 6". However, if this is a flexible liner, you would have to de-rate it 20% for corrugated plus 20% if it offsets. Having said that, you may get an AHJ to sign off on a downsized liner IF the mfr. says its ok. Same as whether or not to use a barometric damper. They are required for oil unless the mfr. specifically forbids them on oil.

That chart was for CAT I gas and says do not use if the connector has the restriction of a vent damper or draft regulator.

Oil liners must be stainless steel. They are not required to be insulated but mfrs. always recommend it. It is considered a good practice for exterior chimneys.

The sizing charts in the NFPA 31 Annex are not part of the code and just FYI. Honestly a smaller liner usually does fine but you must test and just understand that if the liner gunks up with soot, it may backpuff and the ensuing litigation would hang you out to dry.
A slightly undersized liner has nothing appreciable to do with efficiency. Unless the liner is blocked and the house sooted up, it really isn' t that much of a factor on efficiency.

Amazing new technology

@ June 23, 2013 2:19 PM in A new idea

Same people who make the CO angel.

Can't wait to try it when i-phone version released. Curious as to accuracy of course. Amazing what they can do with new technology. I'd want an app such that it alerted my phone even if I have the phone turned off.

Same hotel room strikes again?

@ June 10, 2013 3:09 PM in Same hotel room strikes again?

Wow! What a shame! Where do I start? What caused the CO exposure originally? Who/ how was it "corrected"? Did a qualified person/ agency conduct performance testing to ensure it was acceptable to allow occupancy again? If not CO alarms or monitors in this case, why not? I'm expecting some calls for criminal negligence in this case by the hotel and whomever the service provider(s) is/ are for the combustion appliances.........unless this room is close enough for car exhaust to accumulate and how are they going to rule that out? So many questions.

Anxious to learn facts in this case


@ May 28, 2013 11:59 PM in propane tank location

You need to check to see if NFPA 58 has been adopted by your State into the building codes or if your State Fire Marshal has adopted it. Your local LPG provider can be of assistance in this matter.

Once you have a legal survey, the plat should have been recorded at the courthouse with the legal description. If a neighbor is encroaching on your property or damaging your property, you can sue them either in small claims court or common pleas. If you cannot afford an attorney, you need to contact the bar association and see if they have other resources. You can represent yourself in small claims court but not in common pleas. You may also contact your local fire marshal if you feel there is a safety hazard.

wrongful death case

@ May 20, 2013 5:30 PM in Lofgren case settles...

It is actually rather simple. If you don't want people to wake up dead you:
-promulgate standards based on lab testing, litigation and anecdotal field experience. You constantly monitor and revise those stds. over time
-You develop standardized training curriculae based upon the above, monitor and revise as needed
-you train technicians based upon the above, monitor and re-train as needed but also at regular intervals
-you develop industry certifications based upon the above, which includes written and performance testing after considerable minimum classroom and lab training. You re-cert. every three years which includes min. classroom time and hands-on practical skills
-you develop training and certification for municipal inspectors on the above. You require re-certification every 3 yrs including min. classroom and practical testing.
-You perform an in-house post view inspection of all installations for internal quality assurance. You conduct performance-based testing of all installations to the national stds. With respect to the Lofgren case, that should have included not only inspection of all venting and MUA but a pressure test of the piping, then performance testing of the installation at a national Worst Case std.
-the AHJ requires third party performance testing and inspection before issuing a U&O
-the municipality requires annual inspection by a qualified agency with performance testing every 3 years
-the industry stds. include specific language agreeing on what conditions constitute failure and what triggers repair or replacement.
-that where field testing and anecdotal reports are collected into some qualified agency that monitors such information, catalogues it, shares it with various agencies, Stds organizations, test labs, and mfrs. so that the industry can respond quickly to failures or problems
-that there is a qualified agency overview of all forensic investigators, first responders, EMS, and Fire Officials with respect to incident response, recognition of the cause, documentation of site condtions and preservation of scene materials until a qualified investigator can properly conduct the investigation with accurate and proper reporting to this information pool in a professional and scientific manner, such as NFPA 921 stds.
-That there is an information network established to identify qualified investigators quickly, share information and reporting.

Now, wrap all that up and send it to the ICC, NFPA, ACCA, ARI, PHCC, UL, ASTM, ANSI , ASHRAE and anybody else with a stake in the game and get all this baked into uniform codes and standards. It is absurd that the State of Pa for instance has 2,562 various municipalities that each can have its own local ordinances over and above the Pa Uniform Construction Code (ICC). Plus a lot of these municipalities "opted out" of adopting the I-codes thus are still using some form of the old BOCA codes. Then, you have situations such as the State of Delaware, where stds. adopted by the State Fire Marshal have been upheld in Superior Court as enforceable against contractors. You also have God knows how many air qualify and "green" everything agencies regulating us to death, all under the watchful eye of OSHA and the EPA, for starters.

We can write laws but the jails are full of people who didn't obey them. We can write standards all day but the courts are full of cases where they weren't followed or where those stds. were actually found to be inadequate if not down right hazardous. It all still comes back to people having a conscience about their fellow man.

insulating listed pipe

@ May 2, 2013 6:02 PM in insulating type B vent pipe

Sorry but you cannot wrap B-vent or any listed venting with insulation. Only chimney liners may be wrapped and only the part inside the chimney. The listing on b-vent is based upon a 1" free air space around the vent. When you wrap it, the heat signature of the vent changes as do surface temps. of surrounding combustibles. You also obstruct the exterior of the vent from inspection, which results in the vent going for years rotted out undetected. What you are allowed to do as long as the vent mfr. does not expressly prohibit it would be to encase the vent in a weatherized soffit at stated clearances but with the enclosure open to breathe and using listed pass-throughs for combustible wall penetration at both ends. This will tend to keep the vent warmer in the garage portion but you will need inspection access hatches at every joint. Same for above the roof. If you have several feet of vent exposed above the roof, your condensation may be occurring up there. Constructing a weatherized chase is an acceptable solution.
You can mechanically vent it by attaching an exhaust fan at the termination interlocked with the gas control so the vent is under negative vent pressure but never under positive vent pressure.
What is the avg. Rh% in the CAZ? A soggy house translates to a soggy vent.
Do you have any combustion analysis numbers? If not, you should.
How about you Delta T? If the boiler is extracting too much heat per pass, you may need to adjust your pump pressure or bypass.
Is the CAZ subject to depressurization?
The venting numbers you provided suggest this may not meet the code allowed lateral offset of 75% of the total vent rise.
Any shrouds, obstructions, or adverse local wind effect at the vent termination?
Has the vent been inspected internally? A damaged inner liner can impede venting.
Has anyone put screws into the outer casing of the B-vent? If so, that section is essentially not insulated and voids the 1" clearance to combustibles.
Recommend combustion analysis by certified pro and Level II chimney inspection.

2009 IRC Ch24

@ April 19, 2013 7:29 PM in Running A Gas Line Underground

G2415 has a lot of info. you need to consider. Much depends upon whether or not the conduit ends indoors or outdoors. It must be vented yet protected from rain and insects. If using plastic venting, it will require a min. 18Ga. tracer wire insulated with outdoor direct burial rated tracer wire. The conduit would need to extend at least 2" beyond the slab. The code doesn't properly address popping up in mid-slab for a fire pit or BBQ. The pipe must be buried a min. 12" below grade except 8" min. to each appliance if that installation is "approved' and not susceptible to physical damage. Metallic pipe will need corrosion protection.

That's a blush but I'd recommend really going over whatever codes you have. If this is LP and beyond the second stage regulator, then the regular gas code will apply. Otherwise, refer to NFPA 58 for the LP installation up to the second stage regulator, which would be the "point of delivery".


@ April 19, 2013 12:39 PM in Strange CO problem

When I referred to the 25LF, that was quoting the listed alarm installation instructions--not my recommendation. I agree with your 15LF from sleeping rooms and one per floor including the boiler room. As with that old case "Suicide in Sendai" you can have high levels in the basement, zilch throughout the building except the top floor where the stack effect and/ or mechanical ventilation carries it and it concentrates. I'd rather know its entering the room air right where it happens than wait for it to concentrate hopefully where I have a gizmo to detect it. I'd also rather have my personal alarm alert me to combustible gas leaking in my truck that's about to blow me up.

A new threat is remote car ignitions with attached garages. Whether on purpose or by accident, this represents a very real threat to building occupants. We just had 4 killed in Pa last week by a car running in an enclosed garage. Still trying to get details on that one, whether suicide or accidental.

The message I am getting out about the failings of UL listed CO alarms, whether 2034 single station battery powered store bought alarms or the 2075 central station monitored ones is the alert levels programmed are designed to protect only against CO death and not against CO poisoning. Let that soak in--not only do they fail at protecting against CO poisoning but they are not designed to! The listing plans on you being poisoned to a COHb of at least 10% before it is designed to alert. Gee thanks. That of course ASSumes the alarm is reliable and works as designed, which we know they generally don't. The public has been mislead about these devices.

false alarms with listed CO alarms

@ April 17, 2013 4:38 PM in Strange CO problem

The GRI study back in 2002 noted a very high incidence rate of false alarms and cross-sensitivity to other gases, esp. aliphatic hydrocarbons. If your CO alarm does not have a carbon filter and is a MOS type 1 or type 2 sensor, it probably is very unreliable and susceptible to false positives. Electro-chemical sensors are generally very reliable and not sensitive to false positives or alerts.

Before the NCI course, I had a Kidde Nighthawk with the digital display that would always spike in the 200-400ppm range on the display right after my wife used hairspray.

Central station monitored CO alarms listed to UL 2075 are designed to meet the same parameters as battery powered single point alarms listed to UL 2034, which do not alert until you already have CO poisoning (or it thinks you do). They are designed to alert at 10% COHb, which is the definition of CO poisoning according to most agencies and even though 5% is considered an action level warranting medical treatment. The first symptoms of CO exposure such as headaches typically don't manifest until a COHb of about 15%. Therefore, symptoms of CO exposure are LATE signs and require immediate medical evaluation.

Note that the GRI study found major problems with most listed alarms when the humidity was low. This effect started at about 50%Rh but got severe at 5%.

Since you had a combustion-related operation going, your work could have produced CO or it could have been a false positive. No way of knowing. The recommendation is not to place CO alarms closer than 25LF from a combustion source. However, when working with a torch, it may be prudent to temporarily turn off the alarm by calling the central reporting station, advise them of the work ongoing and ask them to call your cell phone if you have not called them back by a fixed time before leaving the premises unguarded. Then, hang a sign and hang your truck keys on the sign.

Always wear a personal CO alarm. As an alternative, you could place a portable low level CO monitor in the work area. This will respond within 60 seconds and is highly reliable without false positives.

At least someone responded

@ April 11, 2013 6:56 PM in pressure paradox?

I thought of rigging another pressure gauge at that port but didn't have one with me. Will return Monday and test.

Thanks for the reply NBC-one out of 83 looks.

pressure paradox?

@ April 10, 2013 9:01 PM in pressure paradox?

I must be suffering from cerebral flatulence:
WM hot water boiler CG-6-PIDN 175mbh NG> found the Tricator gauge reading about 45 psi static cold but the PRV is not discharging (rated 30psi). Hose thread pressure gauge at boiler drain reads 16 psi. Two story house. Steel expansion tank drained and re-tested-same.

Since it was an old relief valve, I changed it along with a brand new tricator gauge. Re-installed and still reading twice as much at tricator as at drain cock.


polymeric venting approved?

@ April 8, 2013 11:13 PM in Colorado Monoxide Case Moves Toward Trial

The UL STP 103 has investigated listing polymeric venting and has approved the polypro systems primarily because it does not require a site fabricated solvent welded joint. There are other factors but that is a big one as is its higher duty temp. rating. The numbers for max. temps actually vary a bit from mfr. to mfr. so you really shouldn't apply one temp to all PVC. As for the liability angle, the PVC mfrs. have bailed on it. While none have come out and stated they approve of using their product for combustion venting, at least one flatly recommends against it. When an appliance mfr. gets their heater listed with PVC pipe, that mfr. takes on the liability for the venting in a similar way to the mfr. of an 80% furnace approves of single walled unlisted vent connector pipe. The appliance mfr. has tested their make and model appliance to their stds. and found it acceptable. If the listing agency is willing to accept their test data, then they are allowed to grant a listing mark as long as the specific brands and types of PVC, primer, cement, supports, etc. are also spelled out. The ICC has looked the other way on this issue. If a mfr. specs. for instance AL29-4c ss venting, then you can only use those brands listed to UL 1738 but the appliance mfr. and vent mfr. must together provide a suitable adapter to the vent collar. Note that one of the rationale for higher service temps, is not for ordinary use but extraordinary situations such as overfiring. While most venting is not required to withstand catatrophic failures, solid fuel venting is required to withstand a 2,100F chimney fire condition. On the other hand, B-vent is ASSumed to be suitable for CAT I gas yet we know FVIR water heater stack temps can exceed its rating as can oil exceed L-vent's ceiling. What I am most concerned with is the lack of a std. commissioning test methodology for polymeric venting. The PVC mfrs. expressly state do not test their pipe using air pressure under any circumstances so perhaps a hydrostatic test could be developed to prove the patency of joints or leak test it. on site as installed. Maybe we'll end up using test balls like plumbers do for DWV systems. 

2009 IRC

@ April 5, 2013 12:08 PM in Bull head end of T rules/codes

M2101.7 Prohibited tee applications- Fluid in the supply side of a hydronic system shall not enter a tee fitting through the branch opening.

Nothing noted in the IPC about potable water piping and tee orientation.

sad but true

@ March 26, 2013 5:33 PM in Duty of the HVAC technician according to law?

I know we've chatted on this subject a number of times but that recent chase on another site is a good example.

An "inspector" disagreed with my assessment that a gas water heater should have a level II inspection. The WH in question was in a home up for sale. They had foam insulation on both water pipes all the way down and the bottoms were melted from the heat of spillage. He was defending sustained spillage to 15minutes citing ANSI, NFPA and mfrs. instructions.

I cited the NCI course and two studies done by the CPSC on CO incidents involving CAT I gas appliances: see attachments. In them, I note several things they did not. First, there is no uniform reporting mechanism of CO incidents. There are thousands of CO events going unreported all the time. Died of "natural causes"? Yes, CO is natural I guess. How about all the vague illnesses and misdiagnoses? Note that in most cases, a listed CO alarm sounded. Yet there were still CO deaths and all had COHb levels above 10%. The final comments in the second study make my case but it basically says current appliances do not have adequate safeguards against CO spillage and more work needs to be done. Ya' think?

There are a lot of useless tests for draft at drafthoods such as using mirrors, open flames or smoke. None of these can quantify the draft pressure, none of these can quantify the levels of CO spilling and none can verify the actual flow of combustion gases up the vent. Yet they are referenced by the NFGC , ANSI and mfrs. Ridiculous!

We have standards written for technology over 50 yrs old installed into buildings that do not resemble those of that period in terms of house physics and performance and expect a similar outcome? We install appliances that cannot fire and vent without mechanical assistance, put them into cold high mass wet chimneys attached to weatherized buildings with significant negative pressure in the CAZ then wonder why they fail and why the world is going crazy as we live in terrariums.

Unfortunately, the technician is forced to choose between obeying the law vs. doing what he knows works and proves it works through testing.

DIY neighbor fix

@ March 23, 2013 1:27 PM in LOUD Lennox Pulse

If you step onto their property without permission and tamper with their house in any way, you can be arrested for trespass and vandalism.Should someone get hurt as a result of your tampering, you could be charged with criminal charges and go to jail.

Write them a letter return receipt required spelling out the issue in a non-threatening manner and ask them to write back their plan to have the unit inspected by a qualified agency for safety and proper performance then make whatever corrections are required to bring it within a reasonable expectation of operational noise. Give them 15 days to respond. If they do not write back, file a claim in small claims court. You can try the local municipality on a noise ordinance but they usually steer clear of neighbor disputes. If you can document that a pro measured CO coming onto your property from their vent you may have grounds for greater damages as in the loss of use of that portion of your yard. If their fumes are entering your home, call the local fire marshal at once and get yourself a low level CO monitor. Keep in mind if you hire an attorney to sue, you have to think about what damages you think a judge or jury would award. They may find grounds to force the neighbor to fix/ change his equipment with no other damages and you'd be out attorney's fees. Even if you get some damages, just how much do you think you'll be awarded for noise? If you're located in LA's Golden Triangle, it could be substantial. Otherwise, go fish. You may have to erect your own sound barrier or fight back with your own obnoxious sounds,,,,,,,,, until other neighbors sue you. You can set up a strobe light towards his house but if he has a seizure, they'll sue you. '

try written diplomacy first

listed liner connector/ adapters

@ March 18, 2013 8:10 PM in New Chimney liner

Almost all liner mfrs. have a tested listed chimney liner splice/ connector/ adapter for this purpose. If they used one tested and listed by this mfr. in accordance with the mfrs. listed instructions then it is the same and any other section of the liner. If they cobbled a splice together have them pull the liner and use the listed component. Did you take pics? 

uninsulated liners?

@ March 16, 2013 9:53 PM in New Chimney liner

First of all, I consider all my liners insulated. When you pack them tightly top and bottom they are air insulated with a dead air space. I have gone back on many connected to many various types of appliances and I've never found a failed liner. Every liner I've done has been an improvement in flow and draft. Even if the liner ever failed, the brand I use carries a transferrable lifetime warranty. Note that such warranties do not cover labor though. When I reline a very large internal dimension in relation to the liner OD, I do wrap these with a 1/4" foil backed ceramic fiber blanket. FYI, most liners used for heaters are 316Ti alloy and NOT AL29-4c.
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